Due to great progress and popularity of communication technology, the multiplex and high-load optical communication system is widely applied in broadband networks and/or cable TV recently. In an optical communication system, an optical transmitter is in charge of transmitting an optical signal converted from an electric signal, and an optical receiver is supposed to receive an optical signal and relay it to some next stage for being converted into a corresponding electric signal.
Generally speaking, it is more advantageous to integrate an optical receiver and an optical transmitter in a single module to become an optical transceiver for bi-directional operation. FIG. 1 is a schematic view showing an optical bi-directional transceiver system containing double optical fibers, in which a first and a second bi-directional optical transceiver 11a/11b are disposed respectively at each of two ends of the transceiver system, in which a first and a second optical transmitter 13a/13b are responsible for transmitting optical signals while a first and a second optical receiver 14a/14b are responsible for receiving optical signals. As those two bi-directional optical transceivers communicate with each other through a first and a second optical fiber 12a/12b, in which each fiber is in charge of a unidirectional transmission only, therefore, the facility expenditure is more or less uneconomical.
On the other hand, because the application of optical communication system, particularly, a portable and pluggable mini-size optical transceiver to be combined with a personal computer (PC) or a communication equipment, is gradually spread into the field of personal use, a Small Form-Factor Pluggable Transceiver Multi-source Agreement is established as the protocols for regulating the specifications of a mini-size pluggable optical transceiver, an electronic connecting system of optical transceiver, and the layout of motherboard.